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        data-chapter-title="控制代码块"
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                        Flask框架
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                            <b>1.</b>
                        
                        视图及路由
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                            <b>1.1.</b>
                        
                        Flask简介
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                            <b>1.2.</b>
                        
                        虚拟环境
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                            <b>1.3.</b>
                        
                        HelloWorld
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                            <b>1.4.</b>
                        
                        相关配置参数
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                            <b>1.5.</b>
                        
                        路由基本定义
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                            <b>1.6.</b>
                        
                        视图常用逻辑
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                            <b>1.7.</b>
                        
                        正则匹配路由
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                            <b>1.8.</b>
                        
                        异常捕获
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                            <b>1.9.</b>
                        
                        请求勾子
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                            <b>1.10.</b>
                        
                        装饰器路由具体实现
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                            <b>1.11.</b>
                        
                        获取请求参数
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                            <b>1.12.</b>
                        
                        状态保持
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                            <b>1.12.1.</b>
                        
                        Cookie
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                            <b>1.12.2.</b>
                        
                        Session
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                            <b>1.13.</b>
                        
                        上下文
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                            <b>1.14.</b>
                        
                        Flask-Script
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                            <b>2.</b>
                        
                        模板
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                            <b>2.1.</b>
                        
                        Jinja2简介
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                            <b>2.2.</b>
                        
                        模板的使用
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                            <b>2.3.</b>
                        
                        过滤器
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                            <b>2.4.</b>
                        
                        自定义过滤器
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                            <b>2.5.</b>
                        
                        控制代码块
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                            <b>2.6.</b>
                        
                        模板代码复用
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                            <b>2.6.1.</b>
                        
                        宏
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                            <b>2.6.2.</b>
                        
                        继承
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                            <b>2.6.3.</b>
                        
                        包含
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                            <b>2.7.</b>
                        
                        特有变量和函数
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                            <b>2.8.</b>
                        
                        Flask-WTF表单
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                            <b>2.9.</b>
                        
                        CSRF
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                            <b>3.</b>
                        
                        数据库
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                            <b>3.1.</b>
                        
                        ORM
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                            <b>3.2.</b>
                        
                        Flask-SQLAlchemy安装及配置
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                            <b>3.3.</b>
                        
                        数据库的基本操作
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                            <b>3.4.</b>
                        
                        综合案例-图书管理
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                            <b>3.4.1.</b>
                        
                        定义模型
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                            <b>3.4.2.</b>
                        
                        数据库表创建&amp;测试数据添加
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                            <b>3.4.3.</b>
                        
                        数据显示&amp;表单添加
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                            <b>3.4.4.</b>
                        
                        表单验证
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                            <b>3.4.5.</b>
                        
                        删除数据
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                            <b>3.5.</b>
                        
                        多对多演练
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        <li class="chapter " data-level="3.6" data-path="shu-ju-ku/shu-ju-ku-qian-yi.html">
            
                
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                            <b>3.6.</b>
                        
                        数据库迁移
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        <li class="chapter " data-level="3.7" data-path="shu-ju-ku/qi-ta.html">
            
                
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                            <b>3.7.</b>
                        
                        信号机制
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                            <b>3.8.</b>
                        
                        常见关系模板代码
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                            <b>4.</b>
                        
                        蓝图&amp;单元测试
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                            <b>4.1.</b>
                        
                        蓝图
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                            <b>4.2.</b>
                        
                        单元测试
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- for / endfor
</code></pre><h2 id="if&#x8BED;&#x53E5;">if&#x8BED;&#x53E5;</h2>
<p>Jinja2 &#x8BED;&#x6CD5;&#x4E2D;&#x7684;if&#x8BED;&#x53E5;&#x8DDF; Python &#x4E2D;&#x7684; if &#x8BED;&#x53E5;&#x76F8;&#x4F3C;,&#x540E;&#x9762;&#x7684;&#x5E03;&#x5C14;&#x503C;&#x6216;&#x8FD4;&#x56DE;&#x5E03;&#x5C14;&#x503C;&#x7684;&#x8868;&#x8FBE;&#x5F0F;&#x5C06;&#x51B3;&#x5B9A;&#x4EE3;&#x7801;&#x4E2D;&#x7684;&#x54EA;&#x4E2A;&#x6D41;&#x7A0B;&#x4F1A;&#x88AB;&#x6267;&#x884C;:</p>
<pre><code class="lang-python">{%if user.is_logged_in() %}
    &lt;a href=&apos;/logout&apos;&gt;Logout&lt;/a&gt;
{% else %}
    &lt;a href=&apos;/login&apos;&gt;Login&lt;/a&gt;
{% endif %}
</code></pre>
<p>&#x8FC7;&#x6EE4;&#x5668;&#x53EF;&#x4EE5;&#x88AB;&#x7528;&#x5728; if &#x8BED;&#x53E5;&#x4E2D;:</p>
<pre><code class="lang-python">{% <span class="hljs-keyword">if</span> comments | length &gt; <span class="hljs-number">0</span> %}
    There are {{ comments | length }} comments
{% <span class="hljs-keyword">else</span> %}
    There are no comments
{% endif %}
</code></pre>
<h2 id="&#x5FAA;&#x73AF;">&#x5FAA;&#x73AF;</h2>
<ul>
<li>&#x6211;&#x4EEC;&#x53EF;&#x4EE5;&#x5728; Jinja2 &#x4E2D;&#x4F7F;&#x7528;&#x5FAA;&#x73AF;&#x6765;&#x8FED;&#x4EE3;&#x4EFB;&#x4F55;&#x5217;&#x8868;&#x6216;&#x8005;&#x751F;&#x6210;&#x5668;&#x51FD;&#x6570;</li>
</ul>
<pre><code class="lang-python">{% for post in posts %}
    &lt;div&gt;
        &lt;h1&gt;{{ post.title }}&lt;/h1&gt;
        &lt;p&gt;{{ post.text | safe }}&lt;/p&gt;
    &lt;/div&gt;
{% endfor %}
</code></pre>
<ul>
<li>&#x5FAA;&#x73AF;&#x548C;if&#x8BED;&#x53E5;&#x53EF;&#x4EE5;&#x7EC4;&#x5408;&#x4F7F;&#x7528;&#xFF0C;&#x4EE5;&#x6A21;&#x62DF; Python &#x5FAA;&#x73AF;&#x4E2D;&#x7684; continue &#x529F;&#x80FD;&#xFF0C;&#x4E0B;&#x9762;&#x8FD9;&#x4E2A;&#x5FAA;&#x73AF;&#x5C06;&#x53EA;&#x4F1A;&#x6E32;&#x67D3;post.text&#x4E0D;&#x4E3A;None&#x7684;&#x90A3;&#x4E9B;post&#xFF1A;</li>
</ul>
<pre><code class="lang-python">{% for post in posts if post.text %}
    &lt;div&gt;
        &lt;h1&gt;{{ post.title }}&lt;/h1&gt;
        &lt;p&gt;{{ post.text | safe }}&lt;/p&gt;
    &lt;/div&gt;
{% endfor %}
</code></pre>
<ul>
<li>&#x5728;&#x4E00;&#x4E2A; for &#x5FAA;&#x73AF;&#x5757;&#x4E2D;&#x4F60;&#x53EF;&#x4EE5;&#x8BBF;&#x95EE;&#x8FD9;&#x4E9B;&#x7279;&#x6B8A;&#x7684;&#x53D8;&#x91CF;:</li>
</ul>
<table>
<thead>
<tr>
<th style="text-align:left">&#x53D8;&#x91CF;</th>
<th style="text-align:left">&#x63CF;&#x8FF0;</th>
</tr>
</thead>
<tbody>
<tr>
<td style="text-align:left">loop.index</td>
<td style="text-align:left">&#x5F53;&#x524D;&#x5FAA;&#x73AF;&#x8FED;&#x4EE3;&#x7684;&#x6B21;&#x6570;&#xFF08;&#x4ECE; 1 &#x5F00;&#x59CB;&#xFF09;</td>
</tr>
<tr>
<td style="text-align:left">loop.index0</td>
<td style="text-align:left">&#x5F53;&#x524D;&#x5FAA;&#x73AF;&#x8FED;&#x4EE3;&#x7684;&#x6B21;&#x6570;&#xFF08;&#x4ECE; 0 &#x5F00;&#x59CB;&#xFF09;</td>
</tr>
<tr>
<td style="text-align:left">loop.revindex</td>
<td style="text-align:left">&#x5230;&#x5FAA;&#x73AF;&#x7ED3;&#x675F;&#x9700;&#x8981;&#x8FED;&#x4EE3;&#x7684;&#x6B21;&#x6570;&#xFF08;&#x4ECE; 1 &#x5F00;&#x59CB;&#xFF09;</td>
</tr>
<tr>
<td style="text-align:left">loop.revindex0</td>
<td style="text-align:left">&#x5230;&#x5FAA;&#x73AF;&#x7ED3;&#x675F;&#x9700;&#x8981;&#x8FED;&#x4EE3;&#x7684;&#x6B21;&#x6570;&#xFF08;&#x4ECE; 0 &#x5F00;&#x59CB;&#xFF09;</td>
</tr>
<tr>
<td style="text-align:left">loop.first</td>
<td style="text-align:left">&#x5982;&#x679C;&#x662F;&#x7B2C;&#x4E00;&#x6B21;&#x8FED;&#x4EE3;&#xFF0C;&#x4E3A; True &#x3002;</td>
</tr>
<tr>
<td style="text-align:left">loop.last</td>
<td style="text-align:left">&#x5982;&#x679C;&#x662F;&#x6700;&#x540E;&#x4E00;&#x6B21;&#x8FED;&#x4EE3;&#xFF0C;&#x4E3A; True &#x3002;</td>
</tr>
<tr>
<td style="text-align:left">loop.length</td>
<td style="text-align:left">&#x5E8F;&#x5217;&#x4E2D;&#x7684;&#x9879;&#x76EE;&#x6570;&#x3002;</td>
</tr>
<tr>
<td style="text-align:left">loop.cycle</td>
<td style="text-align:left">&#x5728;&#x4E00;&#x4E32;&#x5E8F;&#x5217;&#x95F4;&#x671F;&#x53D6;&#x503C;&#x7684;&#x8F85;&#x52A9;&#x51FD;&#x6570;&#x3002;&#x89C1;&#x4E0B;&#x9762;&#x793A;&#x4F8B;&#x7A0B;&#x5E8F;&#x3002;</td>
</tr>
</tbody>
</table>
<ul>
<li><p>&#x5728;&#x5FAA;&#x73AF;&#x5185;&#x90E8;,&#x4F60;&#x53EF;&#x4EE5;&#x4F7F;&#x7528;&#x4E00;&#x4E2A;&#x53EB;&#x505A;loop&#x7684;&#x7279;&#x6B8A;&#x53D8;&#x91CF;&#x6765;&#x83B7;&#x5F97;&#x5173;&#x4E8E;for&#x5FAA;&#x73AF;&#x7684;&#x4E00;&#x4E9B;&#x4FE1;&#x606F;</p>
<ul>
<li>&#x6BD4;&#x5982;&#xFF1A;&#x8981;&#x662F;&#x6211;&#x4EEC;&#x60F3;&#x77E5;&#x9053;&#x5F53;&#x524D;&#x88AB;&#x8FED;&#x4EE3;&#x7684;&#x5143;&#x7D20;&#x5E8F;&#x53F7;&#xFF0C;&#x5E76;&#x6A21;&#x62DF;Python&#x4E2D;&#x7684;enumerate&#x51FD;&#x6570;&#x505A;&#x7684;&#x4E8B;&#x60C5;&#xFF0C;&#x5219;&#x53EF;&#x4EE5;&#x4F7F;&#x7528;loop&#x53D8;&#x91CF;&#x7684;index&#x5C5E;&#x6027;,&#x4F8B;&#x5982;:</li>
</ul>
</li>
</ul>
<pre><code class="lang-python">{% <span class="hljs-keyword">for</span> post <span class="hljs-keyword">in</span> posts%}
{{loop.index}}, {{post.title}}
{% endfor %}
</code></pre>
<ul>
<li>&#x4F1A;&#x8F93;&#x51FA;&#x8FD9;&#x6837;&#x7684;&#x7ED3;&#x679C;</li>
</ul>
<pre><code class="lang-python"><span class="hljs-number">1</span>, Post title
<span class="hljs-number">2</span>, Second Post
</code></pre>
<ul>
<li>cycle&#x51FD;&#x6570;&#x4F1A;&#x5728;&#x6BCF;&#x6B21;&#x5FAA;&#x73AF;&#x7684;&#x65F6;&#x5019;,&#x8FD4;&#x56DE;&#x5176;&#x53C2;&#x6570;&#x4E2D;&#x7684;&#x4E0B;&#x4E00;&#x4E2A;&#x5143;&#x7D20;,&#x53EF;&#x4EE5;&#x62FF;&#x4E0A;&#x9762;&#x7684;&#x4F8B;&#x5B50;&#x6765;&#x8BF4;&#x660E;:</li>
</ul>
<pre><code class="lang-python">{% <span class="hljs-keyword">for</span> post <span class="hljs-keyword">in</span> posts%}
{{loop.cycle(<span class="hljs-string">&apos;odd&apos;</span>,<span class="hljs-string">&apos;even&apos;</span>)}} {{post.title}}
{% endfor %}
</code></pre>
<ul>
<li>&#x4F1A;&#x8F93;&#x51FA;&#x8FD9;&#x6837;&#x7684;&#x7ED3;&#x679C;&#xFF1A;</li>
</ul>
<pre><code class="lang-python">odd Post Title
even Second Post
</code></pre>
<h2 id="&#x793A;&#x4F8B;&#x7A0B;&#x5E8F;">&#x793A;&#x4F8B;&#x7A0B;&#x5E8F;</h2>
<ul>
<li>&#x5B9E;&#x73B0;&#x7684;&#x6548;&#x679C;</li>
</ul>
<p><img src="../assets/&#x63A7;&#x5236;&#x8BED;&#x53E5;&#x6548;&#x679C;.png" alt=""></p>
<ul>
<li>&#x51C6;&#x5907;&#x6570;&#x636E;</li>
</ul>
<pre><code class="lang-python"><span class="hljs-comment"># &#x53EA;&#x663E;&#x793A;4&#x884C;&#x6570;&#x636E;&#xFF0C;&#x80CC;&#x666F;&#x989C;&#x8272;&#x4F9D;&#x6B21;&#x4E3A;&#xFF1A;&#x9EC4;&#xFF0C;&#x7EFF;&#xFF0C;&#x7EA2;&#xFF0C;&#x7D2B;</span>
my_list = [
    {
        <span class="hljs-string">&quot;id&quot;</span>: <span class="hljs-number">1</span>,
        <span class="hljs-string">&quot;value&quot;</span>: <span class="hljs-string">&quot;&#x6211;&#x7231;&#x5DE5;&#x4F5C;&quot;</span>
    },
    {
        <span class="hljs-string">&quot;id&quot;</span>: <span class="hljs-number">2</span>,
        <span class="hljs-string">&quot;value&quot;</span>: <span class="hljs-string">&quot;&#x5DE5;&#x4F5C;&#x4F7F;&#x4EBA;&#x5FEB;&#x4E50;&quot;</span>
    },
    {
        <span class="hljs-string">&quot;id&quot;</span>: <span class="hljs-number">3</span>,
        <span class="hljs-string">&quot;value&quot;</span>: <span class="hljs-string">&quot;&#x6C89;&#x8FF7;&#x4E8E;&#x5DE5;&#x4F5C;&#x65E0;&#x6CD5;&#x81EA;&#x62D4;&quot;</span>
    },
    {
        <span class="hljs-string">&quot;id&quot;</span>: <span class="hljs-number">4</span>,
        <span class="hljs-string">&quot;value&quot;</span>: <span class="hljs-string">&quot;&#x65E5;&#x6E10;&#x6D88;&#x7626;&quot;</span>
    },
    {
        <span class="hljs-string">&quot;id&quot;</span>: <span class="hljs-number">5</span>,
        <span class="hljs-string">&quot;value&quot;</span>: <span class="hljs-string">&quot;&#x4EE5;&#x68A6;&#x4E3A;&#x9A6C;&#xFF0C;&#x8D8A;&#x9A91;&#x8D8A;&#x50BB;&quot;</span>
    }
]
</code></pre>
<ul>
<li>&#x6A21;&#x677F;&#x4EE3;&#x7801;</li>
</ul>
<pre><code class="lang-html">{% for item in my_list if item.id != 5 %}
    {% if loop.index == 1 %}
        <span class="hljs-tag">&lt;<span class="hljs-title">li</span> <span class="hljs-attribute">style</span>=<span class="hljs-value">&quot;background-color: orange&quot;</span>&gt;</span>{{ item.value }}<span class="hljs-tag">&lt;/<span class="hljs-title">li</span>&gt;</span>
    {% elif loop.index == 2 %}
        <span class="hljs-tag">&lt;<span class="hljs-title">li</span> <span class="hljs-attribute">style</span>=<span class="hljs-value">&quot;background-color: green&quot;</span>&gt;</span>{{ item.value }}<span class="hljs-tag">&lt;/<span class="hljs-title">li</span>&gt;</span>
    {% elif loop.index == 3 %}
        <span class="hljs-tag">&lt;<span class="hljs-title">li</span> <span class="hljs-attribute">style</span>=<span class="hljs-value">&quot;background-color: red&quot;</span>&gt;</span>{{ item.value }}<span class="hljs-tag">&lt;/<span class="hljs-title">li</span>&gt;</span>
    {% else %}
        <span class="hljs-tag">&lt;<span class="hljs-title">li</span> <span class="hljs-attribute">style</span>=<span class="hljs-value">&quot;background-color: purple&quot;</span>&gt;</span>{{ item.value }}<span class="hljs-tag">&lt;/<span class="hljs-title">li</span>&gt;</span>
    {% endif %}
{% endfor %}
</code></pre>

                    
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